It is crucial that an optimal oil supply system be achieved to allow oil to be supplied to sliding portions in order to prevent seizure from occurring at the sliding portions in a piston-type compressor having a crankcase defined by a cylinder block with a plurality of cylinders in which pistons slide formed therein and a housing mounted at the cylinder block, at least one end of a shaft passing through the crankcase rotatably supported at the cylinder block via a bearing and the pistons made to reciprocally slide inside the cylinders by rotating a swashplate disposed inside the crankcase as the shaft rotates.
In particular, when a radial bearing used to support the shaft is constituted with a plane bearing (sliding bearing) in order to minimize the production costs, the bearing and the shaft are bound to slide over a significant area. Thus, seizure will occur readily unless lubricating oil is supplied in sufficient quantity. Accordingly, in a structure proposed in the related art, an isolation space defined by the sliding bearing and a shaft sealing member (a seal member constituted with a lip seal) and made to communicate with the crankcase via a lubricating oil passage present at a front housing, is also made to communicate with the crankcase via a gap between the shaft and the sliding bearing, the lubricating oil in the crankcase is guided into the isolation space via one of the communicating paths and the lubricating oil inside the isolation space is guided back into the crankcase via the other path (see Japanese Unexamined Patent Publication No. 2002-310067)